Without limiting the scope of the invention, its background is described in connection with N-halamine-based rechargeable biofilm-controlling devices. Contamination of materials by microorganisms (e.g., bacteria, fungi, and/or protozoa, with associated bacteriophages and other viruses) is of great concern in the many areas, and in particular to the health care industry where patients are already in a weaken state or are more susceptible to these organisms. It is well known that these microorganisms can survival of on various materials and even transferred between materials, surfaces, animals and humans.
These microorganisms can further accumulate and become embedded in a polysaccharide matrix to form a biofilm that adheres to surfaces (e.g., solid biologic and/or non-biologic surface). Given the unique structure of a biofilm it is not uncommon for microorganisms to express new and sometimes more virulent phenotypes when grown within a biofilm. In addition, microorganisms within biofilms have increased resistance to antimicrobial compounds, even though these same microorganisms are sensitive to these agents if grown under planktonic conditions.
Furthermore, the structure and characteristics of biofilms allow the growth and proliferation of contaminants and result in antimicrobials being readily inactivated or fail to penetrate into the biofilm making the cleaning and removal of pathogenic bacteria, molds, fungi and viruses extremely difficult. The biofilms increase the opportunity for gene transfer between/among microorganisms allowing microorganisms resistant to antimicrobials or chemical biocides to transfer the genes for resistance to neighboring susceptible microorganisms. Gene transfer can convert a previous a virulent commensal organism into a highly virulent pathogen.
The interface between fluids and surfaces has the potential for biofilm development. The turbulent fluid flow over the surface does not provide protection from biofilm development, as evident by biofilm formation in water cooling towers for air conditioners, municipal water storage tanks, private wells, drip irrigation systems and industrial fluid processing operations.
The removal/prevention of biofilms is further complicate in fluid baths, circulating systems and water systems, especially in medical and dental devices were any treatment or agents used to impair biofilm formation must be safe to the patient. The anti-biofilm agent must furthermore not interfere with the characteristics (e.g., manipulability, softness, water-tightness, tensile strength or compressive durability) of a medical device.
Consequently, the formation of biofilms on medical/dental devices, medical implants, artificial organs, catheters, ventilators and dental unit waterline tubes has caused serious consequences. For example, biofilms have been seen on dental unit waterline tubing as far back as 1963. The low flow rate and frequent quiescent periods make the inner surfaces of dental unit waterline tubing are a particularly favorable environment for development of biofilms. Plastic materials used in DUWL such as polypropylene (PP), polyethylene (PE), and polyurethane (PU) are excellent substrates for microbial adhesion and the subsequent proliferation of biofilms. Once formed, DUWL biofilms are very difficult to destroy, and often have caused serious concerns and clinical problems. For example, during dental operations, although the biofilm remains fixed to the tubing wall, microbes in the biofilm can be continuously dislodged into the treatment water, resulting in high microbial counts and a hazard for dental personnel who inhale the aerosolized particles and a health concern for patients who are treated with water.
To treat this problem approaches currently used in the industry include the use of independent water systems, intermittent or continuous chemical treatments, point-of-use filters, sterilizations of water delivery systems, etc. However, none of these methods could completely prevent the formation of biofilms and high microbial counts in DUWLs continue to be concerns in general practice.
The foregoing problems have been recognized for many years and while numerous solutions have been proposed, none of them adequately address all of the problems in a single device, e.g., effectiveness against many forms of bacteria, toxicity, stability and rechargeability.